1. Field of the Invention
The present invention relates to a structure of a bearing for rotatably supporting a shaft (rotating shaft, i.e., driving shaft, transmission shaft etc.) of a mechanical device used in various chemical works, food works etc., for example, a plating works, and a structure of a bushing for rotatably supporting the shaft, the bushing being fit in a bearing hole at need, and aims to provide a split bearing and a split bushing characterized in being made of engineering plastics which is a material particularly excellent in chemical characteristic (e.g., chemical resistance) as well as in mechanical and physical characteristics, the bearing and bushing each having split structure to remarkably facilitate the attachment and exchange of the same.
2. Description of the Related Art
Various mechanical devices used in various kinds of chemical works, food processing works etc. naturally comprise shafts (rotating shafts, i.e., driving shafts, transmission shafts etc.) incorporated therein as a power transmission means, each shaft having gears, pulleys etc. directly fixed thereto and being rotatably supported by way of bearings at some portions thereof. Steel-ball bearings (referred to simply as bearings hereinafter in this section) are mainly used in the works set forth above.
In the above works, e.g., a plating works, various chemical liquids are used in a mechanical device, so that the shafts, bearings, gears, pulleys etc. are always wet being bathed in chemical liquids. As a result, the bearings and other metal components rust and corrode in a very short period of time to cause a trouble in the rotation of shafts and consequently the operation of the whole device, so that the bearings etc. have to be frequently periodically (e.g. every month) exchanged with new ones.
Whereas taking for example exchanging a bearing alone, since a shaft is inserted thereinto, it requires detaching the shaft from the mechanical device and further taking off the bearing, gears, pulleys etc. from the shaft to which they are attached. However, bolts, screws etc. which fix them to the shaft are liable to corrode and rust, and some bolts even have lost their bolt heads to which tools are applied, so that often they have to be inevitably broken to pieces in order to detach them from the shaft since they cannot be detached therefrom easily as they are, which requires considerable dexterity, time and cost.
Particularly in case of the bearings, steel balls therein are liable to be fastened to the shaft with rust due to corrosion. Although the external rail portion thereof and the balls can be detached from the shaft by breaking them into pieces, the internal rail portion thereof directly fixed to the shaft often has to be burnt off by a cutting torch to detach the same from the shaft since shattering them with a hammer etc. is likely to damage the shaft itself, but it requires a considerable dexterity and time in order to prevent the shaft from overheating as well as from being damaged.
Difficult situations in exchanging bearings as set forth above are the same not only in plating works but in other works such as various chemical works, food processing works etc. where the bearings are used in a manner of exposing them to corrosion.
On the other hand, adding to the recent lack of man power, it is a dirty work in a dirty site, and moreover clients complain of a long time consumed, inefficiency and a high wage for a simple exchange of bearing though actually it requires dexterity more than it appears. As a result, servicemen has been decreased in number to largely delay repair on request, and furthermore mechanical devices have to be stopped for a long time for exchange operation, so that the manufacturers have had a very hard time of it.
Although bearings of other familiar plastics such as vinyl chloride etc. have been studied but have not caught much attention since the same construction requires the same trouble of detaching the shaft from the mechanical device and further detaching the gears, pulleys etc. in the same way as the prior art at the time of attachment or exchange of the bearings.
However, recently rapid progress has been made in the research and development of various plastics which are excellent in mechanical, physical and chemical performance for various precision machines and parts and have stable and high reliability free from degradation for a long time of period, i.e., engineering plastics to provide those having mechanical strength, physical characteristics (lubricity, abrasion resistance etc.), chemical characteristics such as chemical resistance (strong acid resistance, strong alkali resistance etc.) and the like which can be used as a bearing for a shaft used in the above various chemical works, food processing works etc. The present invention has been made having an eye on the above progress.